Intended for healthcare professionals

Practice Easily Missed?

Subacute small bowel obstruction or chronic large bowel obstruction

BMJ 2021; 374 doi: (Published 30 July 2021) Cite this as: BMJ 2021;374:n1765
  1. Marc Winslet, emeritus professor of surgery1,
  2. Kevin Barraclough, general practitioner2,
  3. Gregor Campbell Hewson, ED consultant3
  1. 1Royal Free Hampstead NHS Trust and University College London, London, UK
  2. 2Hoyland House, Painswick, Stroud GL6 6TY, UK
  3. 3Emergency Department, Royal Infirmary of Edinburgh, Edinburgh, UK
  1. Correspondence to: K Barraclough k.barraclough{at}

What you need to know

  • Although the features of acute bowel obstruction are usually clinically obvious, the presentation of subacute small bowel obstruction and acute on chronic (large) bowel obstruction may be much more subtle

  • Consider bowel obstruction whenever a patient presents with colicky abdominal pain and recurrent vomiting (especially if prolonged for more than 24 hours), particularly if diarrhoea is minimal or absent

  • Abdominal distension is an important sign with bowel obstruction, but it may be absent if the obstruction is high and may be difficult to detect in obese patients. Vomiting may occur late and infrequently with low bowel obstruction

  • Neither normal bowel sounds nor stool in the rectum excludes the diagnosis

A 48 year old woman presented to her general practitioner with a seven day history of colicky lower abdominal pain and vomiting. The intermittent colicky abdominal pain started first when it woke her from sleep. The next day she vomited twice. Her colicky abdominal pain continued, and she noted that it tended to occur about half an hour after eating. She continued vomiting once or twice a day. She reported no diarrhoeaand had last opened her bowels six days earlier. On examination she was obese, had no abdominal scars, no abdominal hernias, had quiet bowel sounds, and non-specific generalised abdominal tenderness. There was no guarding or rebound tenderness. The rectum was empty. The general practitioner diagnosed constipation and prescribed a laxative. Three days later she was admitted to hospital with recurrent vomiting and dehydration. She was diagnosed with bowel obstruction due to a caecal carcinoma.

What is subacute bowel obstruction?

Sub-acute small bowel obstruction implies an incomplete obstruction of the bowel lumen. Whereas patients with complete bowel obstruction rapidly become extremely unwell, patients with subacute small bowel obstruction or chronic large bowel obstruction may have colicky pain, abdominal distension and vomiting that are less pronounced …

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